Following the fabrication of a semiconductor integrated circuit, the completed device is be attached to a lead frame so as to provide connections to external components through, for example, a printed circuit board (PCB). Moreover, the integrated circuit device is encapsulated in order to protect it from environmental factors as well as to standardize its physical dimensions for the purpose of interfacing with other devices at the component level.
As is well known in the art, increasing circuit complexities, device miniaturization and additional circuit board space limitations have called for smaller and smaller package volumes. It is, therefore, easily understood why it is desirable for the package volume to be as close in size to the encapsulated circuit die as possible.
One of the major problems resulting from conventional packaging processes is the occurrence of voids in the encapsulating material itself. Voids can refer both to holes in the hardened plastic package or to an incomplete package. These voids are believed to occur as a result of a lack of fluidization of the encapsulating material, or by a chase or runner jamming mechanism which may occur when the encapsulating material starts to solidify before it reaches the mold cavity. As additional encapsulating material is forced down the runners, the partially solidified material enters the cavity but fails to completely fill it in. This results in what is sometimes referred to in the industry as the "incomplete fill" problem. As is known in the art, the incomplete fill problem is exacerbated as package thickness is decreased.
Another disadvantage of conventional packaging technologies occurs when constructing multi-chip modules (MCMs). In this case there is often an inability to test each individual component for electrical function prior to the time that the component is encapsulated in the MCM.